Which chemical compound is commonly associated with permanent waving?

Ammonium thioglycolate is widely recognized as a primary ingredient in permanent waving solutions, making it crucial for the waving process. This compound works by breaking the disulfide bonds in the hair's keratin structure, which allows the hair to be reshaped into curls or waves when wrapped around perm rods. After the hair has been processed with ammonium thioglycolate, a neutralizing solution, often containing hydrogen peroxide, is applied to reform the disulfide bonds in their new shape. Therefore, the association of ammonium thioglycolate with permanent waving is well-established in the beauty and cosmetology industry, underscoring its importance in the perming process.

Other compounds listed, while relevant in hair care, serve different purposes. Glyceryl monothioglycolate is another type of thioglycolate used in certain formulations, but it's not as commonly recognized for traditional perming as ammonium thioglycolate. Hydrogen peroxide is primarily used as a neutralizer in the perming process rather than as a waving agent. Sodium hydroxide is associated with chemical relaxers, not perms, making it unsuitable for this specific context.